1. Field of the Invention
This invention relates to a syringe device and, more particularly, to a disposable syringe having an interchangeable needle arrangement while retaining very little fluid following an injection.
2. Description of the Prior Art
The increasing costs of health care have generated many efforts to reduce the cost of devices used to deliver those services. In the case of syringes, a major component of the cost of delivering an injection is often the medication involved. This cost typically far exceeds the purchase price of the syringe itself.
Most of the prior art in the United States utilizes an interchangeable needle assembly known as a "Luer" fitting. This fitting consists of a tapered conical nozzle at the distal end of the barrel, and is most often accompanied by a threaded collar to secure a mating needle assembly to the nozzle. Without the threaded collar the assembly is referred to as a "slip tip", and with the threaded collar the assembly is referred to as a "Luer lock" tip.
Because of the shape of this conical fitting, and the mating recess on the needle assembly, significant amounts of medication are still present in the mating assembly following an injection. It is not uncommon for there to be 0.08 milliliters of medication still in the assembly following an injection. For a 1.00 milliliter injection, this amounts to an extra 8% medication consumed unnecessarily.
An alternative arrangement currently marketed in the United States forgoes the interchangeable needle assembly and permanently attaches the needle to the syringe in such a way that there is very little residual medication. However, this is less desirable because there are a large number of combinations of barrel capacities, needle diameters and needle lengths in use today. For a healthcare facility to carry all permutations in fixed needle format is very expensive. Most healthcare facilities would prefer to carry the components and then mate them as needed.
There is a need to provide healthcare workers with "the best of both worlds"--low residual medication and needle interchangeability.